<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
    <title>Three.js - WebXR - Look to Select</title>
    <style>
    html, body {
        height: 100%;
        margin: 0;
    }
    #c {
        width: 100%;
        height: 100%;
        display: block;
    }
    </style>
  </head>
  <body>
    <canvas id="c"></canvas>
  </body>
<!-- Import maps polyfill -->
<!-- Remove this when import maps will be widely supported -->
<script async src="https://unpkg.com/es-module-shims@1.3.6/dist/es-module-shims.js"></script>

<script type="importmap">
{
  "imports": {
    "three": "../../build/three.module.js",
    "three/addons/": "../../examples/jsm/"
  }
}
</script>

<script type="module">
import * as THREE from 'three';
import {VRButton} from 'three/addons/webxr/VRButton.js';

function main() {
  const canvas = document.querySelector('#c');
  const renderer = new THREE.WebGLRenderer({canvas});
  renderer.xr.enabled = true;
  document.body.appendChild(VRButton.createButton(renderer));

  const fov = 75;
  const aspect = 2;  // the canvas default
  const near = 0.1;
  const far = 50;
  const camera = new THREE.PerspectiveCamera(fov, aspect, near, far);
  camera.position.set(0, 1.6, 0);

  const scene = new THREE.Scene();
  {
    const loader = new THREE.CubeTextureLoader();
    const texture = loader.load([
      'resources/images/grid-1024.png',
      'resources/images/grid-1024.png',
      'resources/images/grid-1024.png',
      'resources/images/grid-1024.png',
      'resources/images/grid-1024.png',
      'resources/images/grid-1024.png',
    ]);
    scene.background = texture;
  }

  {
    const color = 0xFFFFFF;
    const intensity = 1;
    const light = new THREE.DirectionalLight(color, intensity);
    light.position.set(-1, 2, 4);
    scene.add(light);
  }

  const boxWidth = 1;
  const boxHeight = 1;
  const boxDepth = 1;
  const geometry = new THREE.BoxGeometry(boxWidth, boxHeight, boxDepth);

  function makeInstance(geometry, color, x) {
    const material = new THREE.MeshPhongMaterial({color});

    const cube = new THREE.Mesh(geometry, material);
    scene.add(cube);

    cube.position.x = x;
    cube.position.y = 1.6;
    cube.position.z = -2;

    return cube;
  }

  const cubes = [
    makeInstance(geometry, 0x44aa88,  0),
    makeInstance(geometry, 0x8844aa, -2),
    makeInstance(geometry, 0xaa8844,  2),
  ];

  class PickHelper {
    constructor() {
      this.raycaster = new THREE.Raycaster();
      this.pickedObject = null;
      this.pickedObjectSavedColor = 0;
    }
    pick(normalizedPosition, scene, camera, time) {
      // restore the color if there is a picked object
      if (this.pickedObject) {
        this.pickedObject.material.emissive.setHex(this.pickedObjectSavedColor);
        this.pickedObject = undefined;
      }

      // cast a ray through the frustum
      this.raycaster.setFromCamera(normalizedPosition, camera);
      // get the list of objects the ray intersected
      const intersectedObjects = this.raycaster.intersectObjects(scene.children);
      if (intersectedObjects.length) {
        // pick the first object. It's the closest one
        this.pickedObject = intersectedObjects[0].object;
        // save its color
        this.pickedObjectSavedColor = this.pickedObject.material.emissive.getHex();
        // set its emissive color to flashing red/yellow
        this.pickedObject.material.emissive.setHex((time * 8) % 2 > 1 ? 0xFFFF00 : 0xFF0000);
      }
    }
  }

  const pickHelper = new PickHelper();

  function resizeRendererToDisplaySize(renderer) {
    const canvas = renderer.domElement;
    const width = canvas.clientWidth;
    const height = canvas.clientHeight;
    const needResize = canvas.width !== width || canvas.height !== height;
    if (needResize) {
      renderer.setSize(width, height, false);
    }
    return needResize;
  }

  function render(time) {
    time *= 0.001;

    if (resizeRendererToDisplaySize(renderer)) {
      const canvas = renderer.domElement;
      camera.aspect = canvas.clientWidth / canvas.clientHeight;
      camera.updateProjectionMatrix();
    }

    cubes.forEach((cube, ndx) => {
      const speed = 1 + ndx * .1;
      const rot = time * speed;
      cube.rotation.x = rot;
      cube.rotation.y = rot;
    });

    // 0, 0 is the center of the view in normalized coordinates.
    pickHelper.pick({x: 0, y: 0}, scene, camera, time);

    renderer.render(scene, camera);
  }

  renderer.setAnimationLoop(render);
}

main();
</script>
</html>

